1. Field of the Invention
The present invention relates to an information processing apparatus and method and, more particularly, to information processing for protecting intellectual properties (e.g., copyrights) of information data.
2. Related Background Art
Conventionally, as image coding schemes, coding schemes such as Motion JPEG, Digital Video, and the like which use intra-frame coding, and coding schemes H.261, H.263, MPEG-1, MPEG-2, and the like which use inter-frame predictive coding are known. These coding schemes have been internationally standardized by ISO (International Organization for Standardization) and ITU (International Telecommunication Union). Intra-frame coding is best suited to apparatuses which require edit and special playback processes of moving images, since it encodes in units of frames, and allows easy management of frames. On the other hand, inter-frame coding can assure high coding efficiency since it uses inter-frame prediction.
Furthermore, international standardization of MPEG-4 as versatile next-generation multimedia coding standards which can be used in many fields such as computers, broadcast, communications, and the like is in progress.
As such digital coding standards have prevailed, the contents industry strongly recognizes a problem of intellectual property (e.g., copyright) protection. That is, contents cannot be provided with confidence using standards which cannot sufficiently guarantee copyright protection.
To solve this problem, MPEG-4 can describe data in Systems (ISO 14496-1) as Part 1 to build in an IPMP (Intellectual Property Management & Protection) function so as to implement copyright protection in its standards. Refer to ISO 14496-1 for further details.
FIG. 1 shows an example of the format of MPEG-4 encoded data.
Referring to FIG. 1, BIFS (Binary Format for Scene description) encoded data 1010 is obtained by encoding information such as the composition method of object, synchronization of objects, and the like described in Part 1. IPMP encoded data 1011 describes information that pertains to security of bitstreams. Video encoded data 1012 is an encoding result of image data of moving images. Audio encoded data 1013 is an encoding result of audio data appended to moving images.
FIG. 2 shows an example of information described in the IPMP encoded data 1011.
The data 1011 contains information (IPMP object encoded data) indicating encoded data set with security. In FIG. 2, the video encoded data 1012 corresponds to such data. Authentication data used to discriminate if decoding of this encoded data is permitted follows. In FIG. 2, “nonac” is authentication data. In general, this data is enciphered. In this example, the authentication data “nonac” which is provided by reversing authentication data “canon” is enciphered data.
Furthermore, the numbers of frames to be protected and information obtained by enciphering a decipher key in case of that frame data are enciphered by scrambling are described to assure security for some parts of a sequence of video data. In FIG. 2, frame Nos. 1 to 100 in video encoded data can be descrambled by decipher key “key”, and frame Nos. 1000 to 1260 can be descrambled by decipher key “maeda”. The IPMP encoded data 1011 is obtained by encoding these data. The video encoded data 1012 is copyrighted by scrambling frames for which the IPMP encoded data assures security.
FIG. 3 shows an example of a decoding apparatus for decoding such encoded data.
Referring to FIG. 3, an input terminal 1000 receives the IPMP encoded data 1011 and video encoded data 1012 of the encoded data of moving image data. A demultiplexer 1001 demultiplexes the input encoded data into the IPMP encoded data 1011 and video encoded data 1012. A buffer 1002 stores the video encoded data 1012 demultiplexed by the demultiplexer 1001 in units of frames.
An IPMP decoder 1003 decodes the IPMP encoded data. An authentication unit 1004 authenticates decoded data. Selectors 1005 and 1007 change their input source/output destination in accordance with the output from the authentication unit 1004. A descrambler 1006 is connected to the selector 1005. A video decoder 1008 decodes video encoded data to play back image data. An output terminal 1009 outputs playback image data.
The operation of the decoding apparatus with the above arrangement will be explained below.
The IPMP encoded data 1011 is input first from the input terminal 1000. The demultiplexer 1001 inputs the IPMP encoded data to the IPMP decoder 1003. The IPMP decoder 1003 decodes the IPMP encoded data 1011 to obtain authentication data, frame numbers as security objects, and keys for descrambling.
The authentication data is input to the authentication unit 1004 and is compared with authentication data registered in advance. If authentication is unsuccessful, the selector 1005 is directly connected to the selector 1007 not to output decoded data via the descrambler 1006. If authentication is successful, whether or not the selectors 1005 and 1007 are connected via the descrambler 1006 is selected in accordance with an instruction from the IPMP decoder 1003.
In this case, when the IPMP decoder 1003 recognizes encoded data of a frame to which security is given, it instructs the selectors 1005 and 1007 to select a path via the descrambler 1006. Otherwise, the decoder 1003 instructs the selectors 1005 and 1007 to select a path without the intervention of the descrambler 1006.
That is, the selectors 1005 and 1007 select each other as the output and input when authentication is unsuccessful in the authentication unit 1004 and when authentication is successful and the IPMP decoder 1003 determines that the descrambler 1006 is not required (i.e., no processing of the descrambler 1006 is done). On the other hand, when authentication is successful, and the IPMP decoder 1003 recognizes encoded data of a frame to which security is given, the selectors 1005 and 1007 select a path via the descrambler 1006.
Therefore, when authentication is successful, the video decoder can play back a normal image since the descrambler descrambles frames to which security is given in addition to those to which no security is given. When authentication is unsuccessful, since scrambled encoded data is input to the video decoder 1008 which cannot normally decode it, no normal playback image is generated.
However, in this arrangement, IPMP encoded data must be edited upon editing video data, resulting in complicated processes. For example, when a single bitstream is to be generated by combining with another sequence, the frame numbers change, and the contents of the IPMP encoded data must be changed. Key information for scrambling must be prepared independently of security object data, and redundant information must be appended.